The use of antidepressants by breast-feeding women is complicated by limited knowledge about 1) drug presence in breast milk and infant serum and 2) consequences of drug expose to the neonate. No data exist on the clinical significance of infant expose to even negligible amounts of psychotropic medication. The purpose of the research project is to examine psychotropic medication levels in the breast milk of lactating women and in their infants serum, in order to develop psychopharmacologic treatment guidelines for breast-feeding women. The project will follow 24 new mothers on selective-serotonin-reuptake-inhibitor (SSRI) antidepressant medications (sertraline, fluoxetine, and paroxetine). These medications are used for a variety of psychiatric illnesses which worsen in the postpartum, including depression and anxiety disorders. Breast milk and serum samples will be collected and assayed from mediation levels. The assessment of breast milk mediation levels over a 24 hour period will allow determination of time after oral dose when SSRI levels peak. This information will be used to design breast-feeding schedules that minimize infant exposure to medication. Infants will be followed by pediatricians, including a developmental pediatrician, for clinical and neurobehavioral assessments. A control group of 24 euthymic breast-feeding mothers and their infants will be included. During the award period, the candidate proposes an organized program of interdisciplinary training and supervised research under the sponsorship of Dr. Lori Altshuler. Her training in methodologically-sound techniques for the collection of breast milk samples for medication assays, and in the interpretation of assay results, will enable her to make informed recommendations for the pharmacologic management of breast-feeding women. To develop and understanding of etiologic or contributing factors to postpartum psychiatric disorders, the candidate will receive tutorials in reproductive endocrinology. Additional course work and supervision in biostatistics and research design will complement the candidate s scientific career development. This research and career development plan will be the foundation for a future independent investigation of pharmacologic management strategies for psychiatric disorders in postpartum women.